Generally, multilayer glass panels comprise two glass panes and a spacer interposed between the two glass panes to provide an air layer therebetween. Since the multilayer glass panels thus constructed have an excellent thermal insulation capability, they serve as an energy saver when used in combination with housing and building sashes.
According to a most typical process of installing a multilayer glass panel into a sash, a continuous channel-shaped glazing gasket is extruded and cut into lengths that match the vertical and horizontal dimensions of a multilayer glass panel. The glazing gasket lengths are then fitted over the vertical and horizontal edges of the multilayer glass panel, and the vertical and horizontal edges of the multilayer glass panel which are covered with the glazing gasket lengths are inserted into the corresponding grooves of a sash. In this manner, the multilayer glass panel is installed in the sash.
The above process of mounting the glazing gasket on the multilayer glass panel is tedious and time-consuming and is of low productivity because the glazing gasket is manually fitted over the edges of the multilayer glass panel.
For increased productivity, there has recently been proposed a method of molding a glazing gasket onto a multilayer glass panel by extruding a molding material directly onto the peripheral edges of the multilayer glass panel with molding dies which are connected to an extruding machine and shot pumps, as disclosed in WO2006/046349.
A process of molding a glazing gasket onto a multilayer glass panel according to the background art will be described below with reference to FIG. 4 of the accompanying drawings.
FIG. 4 schematically shows in side elevation an apparatus for molding a glazing gasket onto a multilayer glass panel by coating the multilayer glass panel with a molding material. As shown in FIG. 4, the apparatus comprises an extruding machine 1 for melting and extruding a molding material in the form of pellets of thermoplastic resin, a pair of shot pumps 4a, 4b for delivering the melted molding material from the extruding machine 1, the shot pumps 4a, 4b being connected to a molding material outlet of the extruding machine 1 by a molding material supply pipe 2 and a valve 3, a pair of coating guns 6a, 6b for simultaneously applying a layer of adhesive and a layer of molding material to the multilayer glass panel, the coating guns 6a, 6b being connected to respective molding material outlets of the shot pumps 4a, 4b through respective flexible heatable molding material supply pipes 5a, 5b, a pair of shot pumps 8a, 8b for delivering an adhesive which are connected to the coating guns 6a, 6b through respective flexible heatable adhesive supply pipes 7a, 7b, and an adhesive supply pump 11 connected to the shot pumps 8a, 8b by an adhesive supply pipe 9 and a valve 10.
Operation of the apparatus shown in FIG. 4 for coating a multilayer glass panel with a molding material to mold glazing gaskets on the multilayer glass panel will be described below. As shown in FIG. 5 of the accompanying drawings, a multilayer glass panel 21 to be coated with a molding material has its plane oriented vertically and is placed on and held by a support base 13. Of two coating guns 6a, 6b for coating the multilayer glass panel 21 with a molding material, one of the coating guns 6a is disposed closely to the face side of a peripheral edge portion 21a of the multilayer glass panel 21, and the other coating gun 6b is disposed closely to the back side of the peripheral edge portion 21a of the multilayer glass panel 21.
A predetermined amount of melted molding material is supplied from the extruding machine 1 through the molding material supply pipe 2 and the valve 3 to the shot pumps 4a, 4b, and temporarily stored in the shot pumps 4a, 4b. At the same time, a predetermined amount of melted hot-melt adhesive is supplied from adhesive supply pump 11 through the adhesive supply pipe 9 and the valve 10 to the shot pumps 8a, 8b, and temporarily stored in the shot pumps 8a, 8b. Then, the valve 10 is closed and the shot pumps 8a, 8b are actuated to deliver the adhesive stored in the shot pumps 8a, 8b under pressure through the adhesive supply pipes 7a, 7b to the coating guns 6a, 6b. The coating guns 6a, 6b then discharge the supplied adhesive to the face and back surfaces of the peripheral edge portion 21a of the multilayer glass panel 21, thereby coating the face and back surfaces of the peripheral edge portion 21a with respective layers of adhesive. At the same time, the valve 3 is closed and the shot pumps 4a, 4b are actuated to deliver the molding material stored in the shot pumps 4a, 4b under pressure through the molding material supply pipes 5a, 5b to the coating guns 6a, 6b. The coating guns 6a, 6b then discharge the supplied molding material to applied layers of adhesive on the face and back surfaces of the peripheral edge portion 21a of the multilayer glass panel 21, thereby coating the applied layers of adhesive on the face and back surfaces of the peripheral edge portion 21a with respective layers of molding material. One or both of the coating guns 6a, 6b and the multilayer glass panel 21 are moved relatively to each other by a feed mechanism, not shown, so that the coating guns 6a, 6b are continuously displaced along the peripheral edge 12a of the multilayer glass panel 21. The layers 4 of the melted hot-melt adhesive and the layers 5 of the melted molding material are thus continuously applied to the face and back surfaces of the peripheral edge portion 21a of the multilayer glass panel 21, forming glazing gaskets thereon.